PenLayer: Fix pen lines after stamping

Author: adazem009

src/penlayer.cpp

@@ -119,12 +119,13 @@ void PenLayer::setEngine(libscratchcpp::IEngine *newEngine)
 void PenLayer::beginFrame()
 {
     m_fbo->bind();
-    m_painter->beginFrame(m_fbo->width(), m_fbo->height());
+    beginPainterFrame();
+    m_frameChanged = false;
 }
 
 void PenLayer::endFrame()
 {
-    m_painter->endFrame();
+    endPainterFrame();
     m_fbo->release();
 }
 
@@ -149,6 +150,13 @@ void scratchcpprender::PenLayer::clear()
         return;
 
     Q_ASSERT(m_fbo->isBound());
+
+    if (m_frameChanged) {
+        endPainterFrame();
+        beginPainterFrame();
+        m_frameChanged = false;
+    }
+
     m_glF->glDisable(GL_SCISSOR_TEST);
     m_glF->glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
     m_glF->glClear(GL_COLOR_BUFFER_BIT);
@@ -210,6 +218,7 @@ void scratchcpprender::PenLayer::drawLine(const PenAttributes &penAttributes, do
 
     m_textureDirty = true;
     m_boundsDirty = true;
+    m_frameChanged = true;
     update();
 }
 
@@ -220,6 +229,9 @@ void PenLayer::stamp(IRenderedTarget *target)
 
     Q_ASSERT(m_fbo->isBound());
 
+    if (m_frameChanged)
+        endPainterFrame();
+
     m_glF->glDisable(GL_SCISSOR_TEST);
     m_glF->glDisable(GL_DEPTH_TEST);
 
@@ -234,6 +246,11 @@ void PenLayer::stamp(IRenderedTarget *target)
     m_glF->glEnable(GL_SCISSOR_TEST);
     m_glF->glEnable(GL_DEPTH_TEST);
 
+    if (m_frameChanged) {
+        beginPainterFrame();
+        m_frameChanged = false;
+    }
+
     m_textureDirty = true;
     m_boundsDirty = true;
     update();
@@ -415,6 +432,17 @@ void PenLayer::geometryChange(const QRectF &newGeometry, const QRectF &oldGeomet
     QNanoQuickItem::geometryChange(newGeometry, oldGeometry);
 }
 
+void PenLayer::beginPainterFrame()
+{
+    m_painter->beginFrame(m_fbo->width(), m_fbo->height());
+}
+
+void PenLayer::endPainterFrame()
+{
+    m_glF->glViewport(0, 0, m_fbo->width(), m_fbo->height());
+    m_painter->endFrame();
+}
+
 void PenLayer::updateTexture()
 {
     if (!m_fbo)

src/penlayer.h

@@ -64,6 +64,8 @@ class PenLayer : public IPenLayer
         void geometryChange(const QRectF &newGeometry, const QRectF &oldGeometry) override;
 
     private:
+        void beginPainterFrame();
+        void endPainterFrame();
         void updateTexture();
 
         static std::unordered_map<libscratchcpp::IEngine *, IPenLayer *> m_projectPenLayers;
@@ -83,6 +85,7 @@ class PenLayer : public IPenLayer
         mutable libscratchcpp::Rect m_bounds;
         GLuint m_vbo = 0;
         GLuint m_vao = 0;
+        bool m_frameChanged = false;
 };
 
 } // namespace scratchcpprender